Hydraulic control system



NOV. 2, 1965 M E, NERSON 3,214,901

HYDRAULIC CONTROL SYSTEM Filed May 22, 1965 2 ShGnaas-Sheeil 1 @mim A rroRa/r:

Nov. 2, 1965 M. E. IVERSON HYDRAULLC CONTROL SYSTEM Filed May 22, 1963 FIEL E 2 Sheets-Sheet 2 l @ma INVETOR. Monza E .Zi/erna irren/m United States Patent O 3,214,901 HYDRAULIC CONTROL SYSTEM Mourad E. Iverson, Rte. 1, Powers, Mich. Filed May 22, 1963, Ser. No. 282,506 4 Claims. (Cl. 60--19) This invention relates generally to hydraulic control systems, and pertains more particularly to a system for controlling the speed of an internal combustion engine that is drivingly connected to a pump that supplies the systems hydraulic pressure.

One object of the invention is to provide a hydraulic control system for an engine-driven pump that normally permits the engine to idle but which causes an irl-crease in engine speed when load conditions so require.`

Another object is to provide a hydraulic control system that will act rapidly to bring the internal combustion engine to the proper speed for the particular hydraulic load to which the system is subjected, even though such hydraulic load might vary over a relatively wide range.

Another object of the invention is to provide a hydraulic system of the foregoing character that is more sensitive to lower pressures so that the internal combustion engine will begin to change its speed as soon as there is an indication that a greater hydraulic pressure will be needed, even though such indication is at rst quite small.

A further object of the invention is to provide a control system that lends itself readily to various hydraulic valve arrangements that are apt to be encountered in actual practice. In this regard, it is to be appreciated that some valve arrangements operate in decidedly different ways and the hydraulic system in accordance with the teachings of the present invention is easily adapted to the different valve schemes that are in fairly common usage.

Somewhat in connection with the above object, the invention has for an additional feature the use of the control system with internal combustion engines either with or without governors, and also it is within the purview of the invention to utilize the system where a manually actuated throttle setting mechanism is employed.

Yet another object of the invention is to allow the control device forming the basic portion of my hydraulic control system to be employed for the purpose of limiting the maximum pump pressure and the maximum engine speed when the pump is operating under no load conditions. On the other hand, the control device can be connected into the system so as to act as a warning in case there is a leak in the hydraulic circuit.

Still another object of the invention is to provide a hydraulic system that will minimize wear and tear on the internal combustion engine, the pump and the valves incorporated into the system.

These and other objects and advantages of my invention will more fully appear from the following description, made in connection with the accompanying drawings, wherein like reference characters refer to the same or similar Iparts throughout the several views and in which:

FIGURE l is a schematic representation of one form my hydraulic system may assume, and

FIGURE 2 is a modified system in accordance with the teachings of the invention.

Referring now in detail to FIGURE l, the hydraulic control system there depicted has been designated in its entirety by the reference numeral 10. The internal cornbustion engine has been labeled 12 and it will be discerned that it is equipped with a conventional carburetor 14 which has therein a throttle identified by the reference numeral 16.

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The internal combustion engine 12 is drivingly coupled to a pump 18 via a shaft 20. While in some instances it will be desirable to employ an intermediate set of gears between the engine 12 and the pump 18, nonetheless it is to be understood that the pump speed is directly proportional to the speed of the engine 12.

While it is comtemplated that the system will nd utility in conjunction with the operation of various hydraulic devices, for the sake of simplicity only two operating cylinders 22, 24 have been schematically portrayed in the drawing. These operating cylinders 22, 24 contain reciprocable pistons 26 that litt loads 2S and 30, respectively. In actual practice, the cylinders 22, 24 will be of the double acting variety, but as already indicated an effort is herein being made to present the system in as simple a form as is possible. Whereas operating cylinders 22, 24 have been depicted, it will also be appreciated that other hydraulic devices, such as Winches and the like can be substituted therefor.

In the illustrated system, there are two valves 32 and 34, there being only one such valve associated with each of the operating cylinders 22, 24 inasmuch as these cylinders are shown with single acting pistons. Each of the valves 32, 34 include a casing 36 having an inlet port 38, an outlet port 40 and a by-pass port 42. Within the casing 36 in each instance is a segmental valve head 44 which is rotated about a central axis by means of a lever 46. Valves of this general type are in common usage, and therefore the pictured valves are to be considered only exemplary as the specic construction thereof may vary quite widely. Basically, though, it is to be observed that the valve heads 44 can be moved into an annular position in which they block their respective outlet ports 40, thereby allowing Huid ow to occur directly from the inlet ports 38 t0 the by-pass ports 42. However, when the levers 46 are moved in a counterclockwise direction the outlet ports 4l) will be gradually opened and the by-pass ports 42 will be gradually closed.

At this time, attention is called to a sump 48 which serves as a reservoir for the liquid to be pumped through the system 10. Extending into the sump 48 in a suction line or conduit 50. The discharge from the pump 18 is delivered directly into a line or conduit S2 that has direct communication with the inlet port 38 of the valve 32. A short line or conduit 54 extends from the outlet 40 of the valve 32 to the lower end of the operating cylinder 22, and an identical line 54 extends from the outlet port 40 of the valve 34 to` the other operating cylinder 24. A line or conduit 56 extends from the outlet port 42 of the valve 32 to the inlet port 38 of the valve 34. Hence, when the valve 32 is by-passing iluid from the line 52 to the line 56, then the valve 34 will be receiving fluid at its inlet port 33. The by-pass port 42 of the valve 34, however, is connected to a line or conduit 58 that returns the fluid to the sump 48. Obviously, in actual practice there will be a much larger number of Valves 32, 34 that are employed, but the two that have been depicted should provide an adequate basis for the piping arrangement that is contemplated in conjunction with the system 10.

Inasmuch as it is contemplated that the pump 18 will be of a positive displacement type and that there be no by-pass in the pump itself, it is essential in practice to employ a relief valve 60 which is contained in the transverse line or conduit 61 leading from the line 52 and connecting with the line 58. The relief valve 60 will be set for the maximum safe pressure that the system can withstand, say, on the order of 3,000 p.s.i., although other pressures might be selected. It is also to be noted that a check valve 62 has been incorporated into the line 52 to prevent any reverse flow from occurring should the pump 18 fail to deliver an adequate pressure due either to some failure within the pump or to an inadvertent shutdown of the internal combustion engine 12. While the valves 60, 62 have been illustrated as separate and distinct components, valves are available that perform a combined relieving land checking operation.

In 'order to provide the -actual control of the throttle 16 belonging to the engine 12, a takeoff line 64 has communication with the line 52 at its right end and leads to a control device generally denoted by the reference numeral 66. The control device 66 plays a very important role in the practicing of the invention and will now be described in detail. In order to provide a unitary structure, the device 66 includes a vertical plate 68 that is ixedly mounted so as to maintain a cylinder 70 xedly coupled to the take-off line 66. Within the cylinder 70 is a reciprocable piston 72 having a piston rod 74 projecting from the left end of said cylinder. The projecting end of the pist-on rod 74 abuts an arm 76 having a series of holes or apertures 80 formed therein. The lowermost of said apertures 80 is aligned with a fixed clevis 82 that is attached to the plate 68, there being a pin 84 that functions as a pivot point for said arm 76.

The control device 66 further includes a bias rod 86 carrying a clevis 88 at one end which has a pin 90 connecting the clevis 88 to a selected aperture 80 in the arm. The opposite end of the rod 86 from the clevis 88 is threaded and has been identified by the reference numeral 92. The rod 86 is slidably received in an aperture 94 formed in the plate 68.

Attached to the plate 68 circumjacent the aperture 94 is a bushing or collar 96 further serving as a bearing for the reciprocable mounting of the rod 86. A relatively lightweight coil spring 98, that is a spring having a relatively low spring constant, abuts at one end against the collar 96 `and abuts at the other end against a washer 100 carried on the bias rod 86. The amount of compression introduced into the lightweight coil spring 98 can be adjusted initially by a nut 102 threadedly carried on the end 92. A relatively heavy coil spring 104 is mounted concentrically with the spring 98. The relatively high spring constant spring 104 bears at one end against the plate 68 and circumscribes the collar 96. The opposite end of the relatively heavy coil spring 104 is capable of bearing against the washer 100 when the piston 72 has urged the arm 76 sufficiently in a counterclockwise direction.

A linkage mechanism designated generally by the reference numeral 106 is utilized for the purpose of moving the throttle 16. This mechanism 106 includes a Xed clevis at 108 having 4a pin 110 extending through the upper end of a vertical arm 112. The mechanism further includes a connecting rod 114 having a clevis 116 at the right end thereof through which a pivot pin 118 extends, the pin 118 passing through one of the apertures 80 in the arm 76. At the left end of the connecting rod 114 is a second clevis 120 having a pivot pin 122 extending through the vertical arm 112.

Still describing the mechanism 106, it is to be noted that a horizontal arm or link 124 has a pin 126 pivotally connecting the left end thereof to the lower end of the vertical arm 112. The right end of the link 124 is provided with a plurality of holes 128, for the purpose of attaching this end to a clevis 130 through the agency of a pivot pin 132. The clevis 130 is carried at the upper end of rocker arm 134 and the lower end of the arm 134 is attached to a shaft 136 which carries the throttle 16 located within the contines of the carburetor 14.

OPERATION, FIGURE 1 MODIFICATION Having presented the foregoing description, the manner in which the system operates will now be given. When the internal combustion engine is started, it will quickly come up to its normal idling speed. The pump 18 will therefore be driven at a relatively low speed and the pressure developed by the pump will be correspondingly low. The inactive or normal position of the valves 32, 34 is that shown in FIGURE 1 and under these circumstances the liuid under pressure from the pump 18 will flow via the line or conduit 52 into the inlet port 38 of the valve 32 and will continue on through the by-pass port 42 to the inlet port 38 of the valve 34. The valve 34 being in the same position as the valve 32 will permit the fluid to continue on to the by-pass port 42 and it will return to the sump 48 via the line or conduit 58. While only two valves 32, 34 have been pictured, it has already been indicated that a larger number of such valves will be employed in actual practice. Depending upon the number of such valves, the frictional losses will be in accordance with such number and may amount to 70 p.s.i. Even so, this pressure is a relatively low pressure compared to the pressure needed to move the pistons 26 in either of the cylinders 22 and 24.

As a consequence `of the above happening, there will be only a small pressure sensed via the line or conduit 64 and the piston 72 will not be moved appreciably so as to overcome the biasing action of the relatively lightweight coil spring 98. Hence, the linkage 106 will remain in a position such that the throttle 16 will be almost closed. Stated somewhat differently, there is no demand for an increased hydraulic pressure from the pump 18 and the internal combustion engine 12 is maintained at its relatively low idling speed.

Assuming now that the lever 46 of the valve 32 is moved gradually in a counterclockwise direction, it follows that the segmental head 44 will start to close off the by-pass port 42 and will begin to open the outlet port 40, thereby admitting fluid under pressure to the lower end of the operating cylinder 22. Whereas the pressure caused by friction was of the order of 70 p.s.i., the closing of the by-pass port 42 will cause an increase in this pressure. In this regard, an increase in pressure is desired because the outlet port 40 is being gradually opened and depending upon the amount of load 28 a particular pressure will be needed in order to raise this load.

The increase in pressure within the line 52 is sensed by the device 66 and the piston 72 will be urged to the left and the piston rod 74 will bear with increased amount of force against the arm 76. This causes the connecting rod 114 to be moved toward the left and the arm 112 is thereby pivoted in a clockwise direction about the pin 110. This, in turn, moves the link 124 to the left with the consequence that the rocker arm 134 is moved in a counterclockwise direction to open the throttle 16 to a greater degree.

If, for instance, the lever 46 of the valve 32 is moved far enough to cause the head 44 to block completely the by-pass port 42, then it will be appreciated that if the load 28 is quite heavy, the pump 18 is working against the piston 26 and a pressure will continue to be built up in the line 52 and this pressure will continue to be sensed by the control device 66. The greater the pressure that is sensed, the farther the arm 76 will be moved and the farther the throttle 16 will be opened, the linkage 106 transmitting the movement to said throttle 16. As a result, the internal combustion engine 12 will be speeded up to whatever extent is necessary to cause the pump 18 to develop a suicient pressure for the actuation of the piston 26 contained within the operating cylinder 22.

From what has been described, it will be evident that the system 10 takes into account any load requirements with respect to the operating cylinder 22 and its load 28. Considering now the possibility that the operating cylinder 24 will be the one requiring sufficient fluid pressure, then the lever 46 of the valve 32 will be moved back into the position in which it appears in the drawing, thereby preventing reverse flow from the cylinder 22 via the outlet port 40. Under these conditions, the by-pass port 42 will be opened and uid is permitted to ow via the line 56 to the inlet port 38 of the valve 34. Movement of the lever 46 of the valve 34 will then cause the by-pass port 42 of this valve 34 to be gradually closed while the outlet port 40 is being gradually opened. The same action then takes place that occurred when the lever 46 of the valve 32 was moved to cause the head 44 of the valve 32 to admit liquid under pressure to the cylinder 22. The control device 66 functions in the same fashion so that there will always be enough pressure supplied via the line 52 to the valve 34 so that the piston 26 of the operating cylinder 34 will lift the load 30 to the desired extent.

When the loads 28 and 30 are to be lowered, the lever 46 of the valve 32 is moved suiciently in a clockwise direction so as to open all three ports 38, 40 and 42, thereby permitting fluid to flow directly from the inlet port 38 to the by-pass port 42, as well as from the cylinder 22, downwardly through the outlet port 40 to said by-pass port 42. The lever 46 of the valve 34 will, of course, be moved so as to assure continued ow from the inlet port 38 of the valve 34 to the by-pass port 42. If the load 30 is to be lowered, then the lever 46 of the valve 34 will be moved into a clockwise position so as to open the outlet port 40 and provide communication with the by-pass port 42. The angular span of the valve heads 44 is such as to permit fluid to ow downwardly from the cylinder 24 through the outlet port 40 and into the by-pass port 42 with inlet port 38 still open. On the other hand, if the load 28 has already been lowered, then the inlet port 38 of the valve 34 can be blocked by the head 44 of said valve 34 so as to permit ready communication between the outlet port 40 and the by-pass port 42.

Turning now to the modified system shown in FIG- URE. 2, this system having been labeled a, it can be pointed out that the two systems are basically quite similar but do differ in certain respects. Accordingly, it will be helpful to understand at the outset that those parts that do function in a different way or that are somewhat structurally ditferent have been distinguished by the suftix ra Also, as the description progresses, it will be seen that some additional parts or members are utilized in the system labeled 10a.

Instead of leading to the valves 32 and 34, the slightly modified line 52a from the pump 18 conveys liquid under pressure to a nozzle valve 140 via a pipe coupling 142 and a flexible hose 144. The nozzle valve 14), for the sake of illustration, discharges into a storage tank 146 when open.

The control device 66 remains unchanged as far as its specic structure is concerned with respect to both the systems 10 and 10a. However, the linkage mechanism 106a differs in certain aspects and these will now be dealt with. For instance, it will be observed that there is a fixed clevis 108:1 that is located between the connecting rod 114 and the horizontal link 124. It will be recalled that the clevis 108 of FIGURE l was located at the other side of the connecting rod 114. Consequently, the vertical arm 11211 is somewhat dilerent inasmuch as it is contemplated that a throttle setting mechanism 138 be attached to the upper end thereof. The attachment is elfected by reason of a coil spring 140 having one end hooked into a hole or aperture 142 at the upper end Iof the arm 112a. The throttle setting mechanism additionally includes a connector member 144 for attaching a cable 146 to the other end of the coil spring 140. The cable 146 extends through a tube 148 and has at the end thereof remote from the spring 140 a knob 150 which permits the cable 146 to be pulled or moved into any desired position in order to adjust the throttle 16 via the modified linkage 106er.

OPERATION, FIGURE 2 MODIFICATION With the foregoing modified details in mind, it is believed that the operation of the system 10a will be readily understood. Assuming for the moment that the nozzle valve 140 is closed, it can readily be understood that even though the internal combustion engine 12 is operating at a fairly low speed, such as an idling speed, the pump 18 will be acting against a blocked path. Hence, very little speed is necessary to cause the pump 18 to build up a suicient pressure to operate the relief valve 60a. This is the no load condition, for it will be recognized that no uid is being transferred to the storage tank 146. Consequently, there is no need for the internal combustion engine 12 to operate at a relatively high rate of speed, so it is within the purview of the invention to cause the engine 12 to operate at a relatively low speed, more speciically, its idling speed.

With a fairly high pressure exerted on the piston 72 of the control device 66 via the line 52a and take-off line 64, the piston rod 74 will be moved to the left and bears against the arm 76 to cause the connecting rod 114 to move to the left. Due to the fact that the clevis 108e has been placed in a different position from that in FIGURE l, it fol-lows that the vertical arm 112a will be rotated in a counterclockwise direction about the pivot pin 110 of the clevis 108:1. This causes the horizontal link 124 to move toward the right with the result that the throttle 16 is moved toward closed position. This is exactly the goal that is desired, for there is no need to operate the engine 12 at a high rate of speed when there is no hydraulic load being applied to the system 10a.

However, when the nozzle valve 140 is opened, this tends to lower the pressure in the line 52a. Concomitantly with the lowering of the pressure in the line 52a, the pressure is naturally lowered in the cylinder with the result that the piston 72 moves to the right, it being recalled that two coil springs 98 and 104 are compressed when the piston 72 moves suiiiciently to the left. In other words, the coil springs 98 and 104 are exerting their biasing force to return the piston 72 to the right inasmuch as the biasing rod 86 is being moved to the right and is pulling the arm 76 against the projecting end of the piston rod 74. This, in turn, causes the linkage 106:1 to be moved in an opposite direction, which results in the arm 112a being rotated in a clockwise direction about the pivot pin of the clevis 108a. The horizontal link 124 is in this way moved to the left and the rocker arm 134 is, of course, rotated in a counterclockwise direction to open the throttle 16.

The above action continues as long as the pressure is pulled down by having the nozzle valve open so as to discharge fluid to the tank 146. If the nozzle valve 140 is opened to its full extent, then the pressure will be lowered correspondingly and the control device 66 through the intermediary of the linkage 106e will cause the interna-l combustion engine 12 to speed up to the extent necessary to maintain the discharge pressure of the pump 1S at an appropriate Value for maintaining the desired rate of flow.

As soon as the nozzle valve 140 has been closed, it follows that the throttle 16 will again be moved toward its closed position so as to reduce the speed of the internal combustion engine 12. In other words, the pressure in the line 52a will build up and the increase in pressure will act upon the piston 72 to actuate the linkage 106:1 in a direction to move the throttle 16 toward its closed position, as outlined in the early part of the operational sequence pertaining to system 10:1.

Having mentioned the throttle setting mechanism 138, it can be explained that this mechanism 138 permits the throttle 16 to be initially set or adjusted for a given desired speed. Because the spring 140 introduces a yielding action into the system 10a, the control device 16 and the linkage 106e can function in accordance with the intended plan, the spring 140 readily permitting the desired operation to occur. The spring 140, it will be recognized, does contribute somewhat to the biasing action afforded by the coil springs 98 and 104. Consequently, in some refined instances allowance will be made for the additional use of the spring 140 and the springs 98, 104 can be made slightly weaker than they would be if the throttle setting mechanism 138 were not utilized.

With respect to both of the systems and 10a, it should be readily appreciated that when the internal combustion engine 12 is equipped with a governor mechanism, tractors and the like usually having such governors, although trucks normally do not, then the systems 10 and 10a still continue to function in the same manner that has been described. Stated somewhat differently, the governors only attempt to maintain a desired operating speed, but this speed is modified by reason of the throttle control that has been provided via the control device 66 in each system.

It Will, of course, by understood that variouschanges may be made in the form, details, arrangements and proportions of the parts without departing from the scope of my invention as set forth in the appended claims.

What is claimed:

1. In a hydraulic control system:

(a) an internal combustion engine having a throttle associated therewith;

(b) a pump driven by said engine;

(c) a fluid motor operable by said pump; and

(d) means responsive to the pressure supplied said fluid motor for actuating said throttle in accordance with said pressure to increase the speed of said engine to cause said pump to provide a sufficient discharge pressure to operate said fluid motor, said pressure responsive means including:

(1) a cylinder;

(2) a piston reciprocable in said cylinder movable in a direction to actuate said throttle to increase the speed of said engine; and

(3) spring means biasing said piston in an opposite direction to close said throttle, the spring means including a first relatively light coil spring, and a second relatively heavy coil spring.

2. In a hydraulic control system:

(a) an internal combustion engine having a throttle associated therewith;

(b) a pump driven by said engine;

(c) a uid motor operable by said pump; and

(d) means responsive to the pressure supplied said fluid motor for actuating said throttle in accordance With said pressure to increase the speed of said engine to cause said pump to provide a sufficient discharge pressure to operate said fluid motor, said pressure responsive means including:

(1) a cylinder;

(2) a piston reciprocable in said cylinder movable in a direction to actuate said throttle to increase the speed of said engine; and

(3) spring means biasing said piston in an opposite direction to close said throttle, said spring means including a first coil spring having a relatively low spring constant, a second coil spring having a relatively high spring constant, and said first coil spring having a length so as to be acted upon before said second coil spring becomes effective.

3. In the hydraulic control system of claim 1 in which:

(a) said coil springs are arranged so that said piston acts to compress first said first spring and then said second spring While still compressing said first spring.

4. In a hydraulic control system:

(a) an internal combustion engine;

(b) a throttle for controlling the speed of said engine;

(c) an articulate linkage mechanism for operating said throttle;

(d) means for manually adjusting said linkage mechanism including a coil spring attached at one end to said linkage mechanism and a cable connected to the other end of said coil spring whereby said throttle may be set to a desired partially open position;

(e) a pump driven by said engine;

(f) load means connected to said pump; and

(g) means for automatically adjusting said linkage mechanism in response to pressure supplied said load means so as to move said throttle toward closed position to decrease the speed of said engine when said pressure increases sufficiently and to move said throttle toward open position to increase the speed of said engine when said pressure decreases sufficiently.

References Cited by the Examiner UNITED STATES PATENTS 1,259,090 3/18 Ferris et al. 60-19 1,743,005 l/ 30 Resler 60-52 1,981,805 11/34 Kacer et al 60--19 X 2,100,445 11/37 Le Bleu 60-52 X 2,112,466 3/38 Maloon 60-52 2,196,511 4/40 Wagner et al 60-19 X 2,869,325 1/59 Samuely 60-19 X 2,916,880 12/59 Hann 60-19 X 2,931,305 4/60 Stratton 60-19 X JULIUS E. WEST, Primary Examiner.

EDGAR W. GEOGHEGAN, Examiner. 

1. IN A HYDRAULIC CONTROL SYSTEM: (A) AN INTERNAL COMBUSTION ENGINE HAVING A THROTTLE ASSOCIATED THEREWITH; (B) A PUMP DRIVEN BY SAID ENGINE; (C) A FLUID MOTOR OPERABLE BY SAID PUMP; AND (D) MEANS RESPONSIVE TO THE PRESSURE SUPPLIED SAID FLUID MOTOR FOR ACTUATING SAID THROTTLE IN ACCORDANCE WITH SAID PRESSURE TO INCREASE THE SPEED OF SAID ENGINE TO CAUSE SAID PUMP TO PROVIDE A SUFFICIENT DISCHARGE PRESSURE TO OPERATE SAID FLUID MOTOR, SAID PRESSURE RESPONSIVE MEANS INCLUDING: (1) A CYLINDER; (2) A PISTON RECIPROCABLE IN SAID CYLINDER MOVABLE IN A DIRECTION TO ACTUATE SAID THROTTLE TO INCREASE THE SPEED OF SAID ENGINE; AND (3) SPRING MEANS BIASING SAID PISTON IN AN OPPOSITE DIRECTION TO CLOSE SAID THROTTLE, THE SPRING MEANS INCLUDING A FIRST RELATIVELY LIGHT COIL SPRING, AND A SECOND RELATIVELY HEAVY COIL SPRING. 